It's a bastardized version of the idea that we should respect anyone's beliefs. To crib from Patton Oswalt, no you ****ing shouldn't. You acknowledge that other people are ****ty, and then you get in their face and say that's ****ty, and you're ****ty.
Because that's the only way ****ty people become less ****ty. Sometimes it doesn't work, but sometimes it does.
Other people will do stupid things for stupid reasons, but you know what? I'm going to tell them they're doing stupid things for stupid reasons. Deal with it.